Liquid manure has been handled in various ways to insure maximum utility of the manure and minimum waste and runoff. One system of handling liquid manure is to store the manure in tanks or lagoons until it is spread on agricultural land. The manure is pumped with power driven pumping machines from the tanks or lagoons into spreading machines. These machines have transport tanks with fill openings which are relatively large to permit a large volume of material to be discharged into the tanks. The openings are sufficiently large to allow the operator to enter the tank as well as permit large objects and bulk materials to enter the tank. The operator can also accidentally fall into the tank through the large inlet opening. When large solid objects, as rocks, bones, lumber, hard solid manure, frozen liquid manure and the like, are allowed to enter the tank chamber, the pumps, augers, valves and nozzles of the machine will become clogged and inoperative. The machine may be damaged by the solid objects, thereby requiring costly repairs. In use, the tank chamber accummulates noxious gases emitted by the manure which can be fatal to humans. In order to service, clean and repair the machines, operators often enter the tank chamber without adequate protection from the gases in the chamber. This results in a hazard to human health.
The tanks have pumping units operable to remove the manure from the tank and discharge the manure onto a desired location. Some tanks are provided with pumps which supply air under pressure to the tank whereby the manure in the tank is subjected to pressure to force the manure through a discharge nozzle onto the desired location. The discharge structures have manually operated valves in the discharge line which are open prior to spreading the manure. The valves are manually closed when the spreading is terminated. Examples of liquid manure spreading machines are shown in U.S. Pat. Nos. 3,420,452 and 3,528,612.